That's true of bottled bleach, but this stock solution is not the same thing as bottled bleach. "Straight" bleach is highly alkaline due to the addition of sodium hydroxide. This high pH favors a form of stable form of hypochlorite.

However, once you dilute it with water (like this stock solution), the reactive form predominates and it very quickly breaks down. I'm assuming that calcium hypochlorite will react similarly to sodium hypochlorite found in household bleach.

Diluted bleach solutions are often used in labs as a cheap sanitizer, but any lab SOP will mention that this solution should be thrown out and a fresh batch made if it is older than 12-24 hours old due to loss of sanitizing potency.